Pediatric Red Marrow and Organ Radiation Dose Estimates in Computed Tomography from Monte Carlo Simulations

Abstract

Radiation dose calculations are essential to understanding the balance between the benefits and risks of diagnostic imaging procedures. Red marrow is also a highly radiosensitive organ and of great interest especially for pediatric patients. A Monte Carlo code built with the GEANT4 tool kit was developed to simulate pediatric patients undergoing CT examinations at Monroe Carell Jr. Children's Hospital at Vanderbilt. Patient-specific voxel computational phantoms were created from segmentation of previously acquired pediatric patient images. A series of deformable pediatric reference NURBS phantoms was developed for a large range of ages, percentiles, and reference anatomy. Individual bones were modeled using age-dependent factors, and red marrow distributions were modeled as a function of age. Organ and effective doses were calculated for pediatric patients receiving chest-abdomen-pelvis CT exams. These dose estimation methods offer the ability to predict patient dose prior to and after CT examinations, and physicians and scientists can use this information in their analysis of dose prescriptions for particular subjects and study types. This may lead to practices that minimize radiation dose while still achieving high quality images and, ultimately, improved patient care.